Re: Gate A20

[erich]

"Yoshinori K. Okuji" <address@hidden> wrote:

> About Gate A20.
> 
> GRUB supports only the traditional approach (i.e. using the keyboard
> controller) to enable/disable Gate A20 at the moment. This is not
> enough.

...[examples deleted]...

> Therefore, syslinux uses BIOS as the first way, the keyboard
> controller as the second, and System Control Port A as the last. This
> may be good for syslinux, but not good for GRUB, because GRUB must
> support interactive operations using a keyboard even after loading an
> OS image, unlike syslinux. In Daniel's system, as using the keyboard
> controller spoils the BIOS support for an USB keyboard, System Control
> Port A _must_ be used before the keyboard controller. Incidentally,
> his system doesn't support the BIOS calls (INT 15H, AX=240x)
> unfortunately.
> 
> I'm not sure how we should solve all this problem. Do you have any
> ideas or suggestions?

Ironically, I've been hacking on the Keyboard controller support in
GRUB recently (due in part to wanting to understand it better).  I
have a fix or two nearly ready to send in (I found I could cause
problems by pounding on the keyboard right as GRUB is starting up on
some systems), but I was investigating syslinux's and Linux setup's
method in this process and saw a variant on what you have listed
above.

One question that I was going to look at is how Windows does it...
that is probably the "best tested" method.

Does someone one the list know already?

--
    Erich Stefan Boleyn     <address@hidden>     http://www.uruk.org/
"Reality is truly stranger than fiction; Probably why fiction is so popular"